| Biochemical and genetic characterization of wheat (Triticum spp.) kernel polyphenol oxidases Journal of Cereal Science 44:353-367 |
| Anderson,J.V.,Fuerst,E.P.,Hurkman,W.J.,Vensel,W.H.,Morris,C.F. |
| Genetic variability of polyphenol oxidase (PPO) activity was evaluated in hexaploid, tetraploid, and aneuploid wheat (Triticum spp.).
A DNA probe to kernel-specific PPO hybridized to PPO clones from an immature wheat kernel cDNA library but not to clones from a
seedling cDNA library. Recombinant protein and antibody were developed from the kernel-specific PPO. PPO transcript and antigenic
proteins were most abundant during kernel development and decreased rapidly at physiological maturity. PPO proteins were more
abundant in immature kernels, but PPO activity was greater in mature kernels. Wheat kernel antigenic protein bands of 58, 60, 62, and
75kD were identified; immunoprecipitated proteins of 60 and 62kD were confirmed to be PPOs by LC-MS/MS. The 2D
chromosome was implicated as a major locus of PPO activity in cultivar (cv.) ‘Chinese Spring’ based on antigenic staining intensity of
60–62kD proteins and kernel PPO activity in aneuploid lines. The 58kD protein was not well-correlated with kernel PPO activity,
while the 75kD protein was likely a PPO precursor. Tropolone completely inhibited PPO activity extracted from mature kernels but
not from immature kernels. Total PPO activity in mature kernels is thus a function of specific PPO isoforms present, their abundance,
and activation levels.
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